When an object orbits around another object, in the path of a circle
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What holds the planets and satellites in their circular orbit around the sun/other planets?
The force of the gravity
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What are artificial satellites and what is their orbit like?
Man-made satellites
Force of gravity holds them in orbit
Geostationary satellites orbit once every 24 hours so they always face the same part of earth
Other artificial satellites orbit more frequently
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Why does the force gravity lead to a change in velocity in circular orbit of a satellite?
The force of gravity causes the satellite to accelerate. The acceleration causes a change in direction.
The direction is continuously changing so the velocity is continuously changing
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If the speed of the satellite changes, then the _______ of the orbit must also change
(in a stable orbit).
If the speed of the satellite changes, then the RADIUS of the orbit must also change (in a stable orbit).
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If the speed of the satellite increases, the radius of the orbit _________.
Why?
If the speed of the satellite increases, the radius of the orbit DECREASES.
At higher speeds, the satellite needs greater force of gravity to prevent it flying off into space, so by moving closer to earth, gravitational force=greater
This is true for moon
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What is the red-shift effect?
Light from distant galaxies have an increased wavelength compared to light from nearby galaxies.
The further away the galaxies, the faster they are moving and the bigger the observed increase in wavelength.
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The larger the redshift, the ________ the galaxy is moving
Nearby galaxies are moving _______ than further galaxies
The larger the redshift, the FASTER the galaxy is moving
Nearby galaxies are moving SLOWER than further galaxies
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What does the observed red-shift provides evidence for?
The fact that distant galaxies are moving faster than nearby galaxies provides evidence for the idea that space itself (the universe) is expanding and supports the Big Bang theory.
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What is the Big Bang Theory?
The idea that the universe began from a very small region that was extremely hot and dense, which then expanded into the universe that we see today
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How do we know that the universe is expanding faster?
Astronomers assumed that gravity would cause the expansion of the universe to gradually slow down, but observations of a supernovae has showed that the rate of expansion is increasing
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What is a possible explanation of the universe expanding faster?
Scientists have suggested that there is matter/energy in the universe that we cannot detect. This is dark matter and dark energy.
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Other cards in this set
Card 2
Front
What holds the planets and satellites in their circular orbit around the sun/other planets?
Back
The force of the gravity
Card 3
Front
What are artificial satellites and what is their orbit like?
Back
Card 4
Front
Why does the force gravity lead to a change in velocity in circular orbit of a satellite?
Back
Card 5
Front
If the speed of the satellite changes, then the _______ of the orbit must also change
(in a stable orbit).
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